This proposal will address two major questions critical to the understanding of the structure and physiology of vaginal epithelium. These are: 1) What is the nature of the permeability barrier in vaginal epithelium?, and 2) What are the properties of the vaginal cell surface that influence the adherence of bacteria to the cells? To test the hypothesis that intercellular substances may form part of the permeability barrier, histochemical and cytochemical studies will be conducted to demonstrate the nature and localization of lipids, glycoconjugates, and lysosomal enzymes in human and monkey vaginal epithelium. The results will be compared to localizations found in other keratinizing and non-keratinizing epithelia. Permeability barriers in intact epithelia will be further examined by injecting electro-dense tracer molecules (lanthanum and peroxidase) into the lamina propria of monkey vagina and following by electron microscopy the movement of the tracers into the epithelium. Similar experiments will be carried out with topically applied tracers to examine permeability barriers of the surface cells. Human vaginal epithelium will be grown to confluence in a cell culture system and the morphological differentiation, cytochemistry and permeability of this epithelium will be examined by similar techniques and compared to non-cultured epithelium. To study bacterial adherence to the cultured epithelium, optimal concentrations of Lactobacillus will be added to the cultured epithelium and their adherence quantitated. The effects of pH, temperature, divalentcations, and modification of cell surface carbohydrates on adherence will be measured.